Field of the Invention. This invention relates to yarns of bicomponent filaments suitable for use in arc protection, wherein each filament has a distinct region of aramid polymer having discrete carbon particles homogeneously dispersed therein and a distinct region of modacrylic polymer being free of discrete carbon particles.
Description of Related Art. U.S. Pat. No. 4,803,453 to Hull discloses melt-spun filaments having antistatic properties comprising a continuous, nonconductive sheath of a synthetic thermoplastic fiber-forming polymer surrounding an electrically conductive polymeric core comprised of electrically conductive carbon black dispersed in a thermoplastic synthetic polymer.
U.S. Pat. No. 4,309,476 to Nakamura et al. discloses a core-in-sheath type aromatic polyamide fiber having satisfactory dyeing properties made from a single aromatic polyamide material. When the core-in-sheath fiber is dyed with acid dyes, only the sheath portion is colored. U.S. Pat. No. 4,398,995 to Sasaki et al. discloses the use of the fiber of Nakamura in a paper.
U.S. Pat. No. 3,038,239 to Moulds discloses improved composite filaments that have crimp reversibility. The filaments have at least two hydrophobic polymers in eccentric relationship, wherein one of the hydrophobic polymers further contains mixed therewith a minor amount of polymer having a high water absorption rate.
U.S. Pat. Nos. 7,065,950 and 7,348,059 to Zhu et al. disclose a yarn, fabric, and garment for use in arc and flame protection that contains modacrylic, p-aramid, and m-aramid fibers. While these fiber blends have been found to be very useful in arc protection, any improvement in arc protection is welcomed as it can potentially save lives.